The present invention relates to a safety device for vehicle brakes and more particularly pertains to a safety device for spring brakes which prevents the disengagement of the two chambers.
A conventional spring brake generally comprises a first chamber, a second chamber, a diaphragm, a spring and a pushrod connecting to a braking device such as a brake shoe or brake pad. The diaphragm is placed between the two chambers. The spring is heavily coiled between the diaphragm and the bottom of the first chamber. By controlling the amount of air pressure applied to the diaphragm and thereby controlling the compression of the spring, the driver can apply or release the brake. As a significant amount of energy is stored in the coiled spring, it is vital to hold the two chambers and the diaphragm in place to prevent the spring from bursting out of the first chamber.
To this end, a conventional spring brake is typically equipped with a clamp band to engage the two chambers together with the diaphragm in between. However, if a user inadvertently loosens or disassembles the clamp band by loosening a screw thereon, or if the clamp band is loosened accidentally owing to, for example, a bump to the vehicle, or if the clamp band becomes out of order and fails to engage the chambers properly, the diaphragm is no longer securely fastened and thus can no longer keep the spring in place. As a result, the spring together with the diaphragm and the second chamber may burst away from the first chamber. In such a case, anybody in the surrounding area may be injured or even killed by the parts bursting away from the first chamber, let alone damage is likely to be caused to properties in the neighborhood.
With a view to preventing such incidents, some spring brakes have the housing of the first chamber and the clamp band being cast as one integral body. The second chamber is fastened to the first chamber by the method of spinning. The two chambers are then permanently joined together. Although such arrangement can prevent any accidental disengagement of the two chambers, it is susceptible of higher production costs and lower manufacturing efficiency. Moreover, if any component has any defect or if there is any error or abnormality during the assembling procedures, the air brake may fail to function properly and may not be repaired and will have to be disposed of, which results in a waste of resources.